This non-provisional application incorporates by reference the subject matter of Application No. 2001-312702 filed in Japan on Oct. 10, 2001, on which a priority claim is based under 35 U.S.C. xc2xa7119(a).
1. Field of the Invention
The present invention relates to a vehicle body structure in which a roof side rail is comprised of a part at an upper edge of a vehicle body side opening, which is opened and closed by a sliding door, and a part at a front side thereof. In particular, the present invention relates to a vehicle body structure in which a roof side rail is comprised of a reinforcing member.
2. Description of Related art
To ensure durability and inhibit deformation when overload is applied to vehicles in collision, the vehicles are configured to maintain sufficient stiffness while enabling a reduction in weight. In particular, a front pillar of a vehicle and a roof side rail formed continuously from the front pillar are each formed to have a closed section to achieve a high stiffness in order to inhibit excessive deformation in frontal collision and offset collision. A reinforcing member is disposed inside the closed sections of the front pillar and the roof side rail, and they are integrated to inhibit deformation when overload is applied to the vehicle in collision. Prior art related to this technique is disclosed in Japanese Laid-Open Patent Publication No. 2001-10533.
As shown in FIG. 6, however, the foregoing prior art cannot easily be applied to a vehicle body structure in which a front opening 120 and a rear opening 130 partitioned by a center pillar 110 are formed in a vehicle body side 100, and the rear opening 130 is opened and closed by a sliding door, not shown as described below in detail.
As shown in FIGS. 6-9, a roof side rail 140 is opposed to respective upper edges of the front and rear openings 120 and 130, and has the front end thereof connected to a front pillar 150 and the rear end thereof connected to a rear pillar 160. The roof side rail 140 is formed with a space 180 at the center of its section in order to avoid interference with an arm having a roller provided in the sliding door, not shown, and a guide rail 170 intended to guide the roller. Thus, in the roof side rail 140, the sectional area of the closed section of a part opposed to the upper edge of the rear opening 130 is smaller than the sectional area of the closed section of a part opposed to the upper edge of the front opening 120, and the part opposed to the upper edge of the rear opening 130 is deviated toward the center of the vehicle body. Therefore, a step part D is formed in the vicinity of the upper side of the center pillar 110 that connects the front opening 120 and the rear opening 130 to each other.
As described above, in the vehicle body structure in which a rear door is a sliding door 200, the part of the roof side rail 140 opposed to the upper edge of the front opening 120 and the part of the roof side rail 140 opposed to the rear opening 130 are different in sectional form, and the front opening 120 and the rear opening 130 are connected to each other via the step part D as shown in FIGS. 7, 8, and 9. In this case, as shown in FIG. 6, an axis y2 (refer to an axial line L2) opposed to the upper edge of the rear opening 130 is greatly deviated from an axis of the part opposed to the upper edge of the front opening 120, i.e. an axis y1 (refer to an axial line L1) corresponding to the center of the stiffness at which a compression force and a tensile force are balanced to offset each other in the direction of the section (indicated by xcex4 in FIGS. 6 and 9).
Therefore, when overload is applied to the roof side rail in the axial direction in frontal collision or offset collision, the step part D deviated to the largest degree is most likely to be affected by a bending action, and the roof side rail is easily bent from the step part D.
In view of the above, it would therefore be desirable to provide a vehicle body structure which is capable of improving the stiffness of a roof side rail, along which is disposed a guide rail that guides a sliding door.
Further, according to the present invention, the vehicle body structure using the sliding door increases stiffness by improving the sectional coefficient of a roof side rail by a pipe-shaped reinforcing member.
To attain the above object, in the present invention, a reinforcing member is disposed in the cross section of the roof side rail and has a closed section such that a cross-sectional area of a part proximal to the rail member is different from a cross-sectional area of other part.